ALPAQA: Advanced Network Links with a Photon-Atom Quantum Transduction Apparatus

Context: Today’s society relies heavily on fast and reliable computation interconnected securely over the internet. Quantum networks promise to revolutionise these technologies, transmitting and processing quantum information while exploiting entanglement and quantum measurement to achieve performance beyond the reach classical systems. Amongst the many promising material platforms for building quantum networks, trapped strontium ions (Sr+) are emerging as a leading quantum computing architecture, while semiconductor quantum dots (QDs) are prominent single photon sources. However, Sr+ emit photons in the near ultraviolet (NUV) and QDs have shown excellent performance in the near infrared (NIR) – wavelengths that are subject to significant propagation losses in optical fiber, thereby severely limiting the operational distance of the quantum network. I will address this issue with a quantum transducer – a device that can efficiently convert photons from the UV and NIR to the low-loss telecommunication wavelengths in optical fibres, paving the way for heterogeneous quantum networking. Aims/Objectives: The primary aim of my proposal is to build and exploit advanced networking links using efficient light-matter interactions with a warm rubidium vapour. To achieve this, I will utilise my expertise in quantum light-matter interactions and leverage the successes of Phase I of my fellowship, where I demonstrated an ultrafast, high-efficiency, low-noise quantum memory at telecom wavelengths. Phase II of my fellowship will deliver the world's first single-stage convertor of NUV quantum light to telecoms wavelength, which will allow strontium ion quantum computers to be compatible with optical fiber communication networks. The device will have the additional utility to convert near infrared quantum light from semiconductor quantum dot sources, while also functioning as an on-demand storage device. Finally, the device will be built for field deployment, enabling quantum conversion to be done in collaboration with project partners based in Southampton and Oxford. In achieving this ambitious aim of my fellowship, the objectives are: I. Build field-deployable 19-inch rack mounted quantum light-matter interfaces, II. Demonstrate quantum transduction from NUV and NIR to telecom, III. Perform hybrid quantum light-matter operations. Potential Applications: In the same way the invention of the transistor led to rapid advances in computation and communications, revolutionising the 20th century, quantum networks are the underpinning technology that have the potential to bring significant change and long-term social-economic impact in the 21st century. Such networks enable inherently secure communication for online transactions in banking, retail and the stock market, more precise global clock synchronization for enhanced GPS accuracy, and the potential to extend telescope baselines for improved astronomical observations. Networked quantum objects form powerful quantum computers capable of solving problems that current computers cannot, potentially revolutionising research methods in healthcare, pharmaceuticals, and green energy. Efficient simulations and optimised computations using quantum networks could benefit epidemiology and genetic research, reduce costs in medication design for new diseases, and improve artificial light-harvesting devices for alternative energy sources, with many more applications likely to be discovered in the coming decades. In the shorter term, my project will aid in training the next generation of quantum scientists and generate valuable IP to be exploited by spinout companies, further forwarding the emergent quantum technologies industry in the UK.